\documentclass{article}
\usepackage{amssymb,amsmath,amscd,concmath}
\pagestyle{empty}
\begin{document}
\begin{equation*}\begin{displaymath}\int\frac {d\theta}{1+\theta^2} 
=\tan^{-1} \theta+ C\end{displaymath}
equation\end{equation*}
\end{document}
